These yoga poses are indeed good for strengthening the core or ab muscles but this is not weight loss. For weight loss, you have to burn your excess calories and fat. The ways to do that is -
* build muscle - muscle requires more energy to be 'maintained' - but this is a long process. You can't put on 3 kgs of muscle in 2 months - it'll take a year.
* Cardio exercises - run, cycle, skip, dance, jump, swim - anything that moves your body vigorously. This is the best (and probably the only sure fire) way to burn fat and lose weight.
